The present invention relates to a hysteresis circuit suitable for a voltage-controlled oscillator or a Schmitt circuit.
Japanese Patent early publication No. 53-14285 discloses a hysteresis circuit which is provided with a differential pair of first and second transistors for voltage comparison. In this circuit, an input signal is supplied to the base of the first transistor and an output voltage of a voltage divider circuit connected across a reference voltage source is supplied to the base of the second transistor. The voltage divider circuit includes a switching transistor which is turned ON and OFF according to the input signal voltage. The base voltage of the second transistor is thus switched between a high voltage V.sub.H and a low voltage V.sub.L.
With this circuit it is difficult to obtain a high speed response because the switching transistor driven into saturation is used. Also, power dissipation increases since a reference voltage source is necessary.